1. Field of the Invention
The present invention generally pertains to a device for estimating the lifetime of one or several wire harnesses subjected to repeated bending. The device allows a count of the number of repeated bending cycles prior to the breakage of the wire harnesses concerned. The count gives an estimation for the durability of the wire harnesses in question. Wire harnesses which are the subject-matter of the present invention are used e.g. in the doors of vehicles, where they are subjected to repeated bending.
2. Description of Background Information
Wire harnesses are employed, for example, for connecting diverse electrical apparatuses to a battery mounted in a vehicle. Such wire harnesses are formed by bundling together a plurality of electrical cables. When a door of a vehicle is opened or closed, or when an adjustable seat is slid back or forth, a wire harness employed therein is subjected to repeated bending forces. The latter are usually imparted on the wire harness through some localized bending sites therein. Studies on such a wire harness have already been described e.g. in Japanese Patent Applications published under Nos. Hei 4-229 506, Hei 6-278 460 and Hei 11-263 175.
In general, when a wire harness receives bending forces, there is a high risk that the localized bending sites mentioned above will be broken. The device of the present invention is contemplated to estimate the lifetime or durability of a wire harness including such localized bending sites.
As a common bend test, a relevant part of, e.g. a door of a vehicle is cut out as it is, and a wire harness is tested on that part. The number of bending cycles which leads to the breakage of the harness is then counted in order to estimate its durability.
In the above case however, the relevant part must be first procured from a car body, which requires time and expenses.
Accordingly, there is proposed a device simulating the above-mentioned relevant part of a car. Such a device includes two panels or frame units connected through a hinge unit. A wire harness is then held by a grommet, and the two panels or frame units are repeatedly opened and closed by means of a hydraulic cylinder. A device simulating a car""s relevant part, as in the present case, is already disclosed e.g. in Japanese Patent Application published under No. Hei 7-146 226.
However, the above device can handle a bend test on only one sample at a time. Consequently, the same bend test has to be repeated many times, in order to collect a sufficient amount of test data. Such a method consumes much time and lacks efficiency.
It is therefore an object of the present invention to provide a bend test device for wire harnesses, capable of handling a plurality of samples at the same time.
To this end, there is provided a bend-test device for bending at least one wire harness repeatedly, in order to determine the number of bending cycles leading to a breakage in the wire harness. The bend-test device includes a first harness-holding unit, a second harness-holding unit and a hinge unit having a fulcrum axis, the first and second harness-holding units being connected through the hinge unit in a freely pivotable manner around the fulcrum axis.
According to the present invention, the first harness-holding unit includes a fixed frame unit including at least one first panel which carries at least one first holder configured to hold a wire harness. The first panel, when there are more than one, are arranged substantially in a parallel relation to each other, and aligned substantially perpendicularly to the direction of the fulcrum axis.
The second harness-holding unit includes a mobile frame unit including at least one corresponding second panel which carries at least one second holder configured to hold the wire harness. The at least one second panel is arranged in correspondence with the at least one first panel.
The bend-test device further includes a pivoting mechanism that pivots the mobile frame unit reciprocating manner relative to the fixed frame unit, so as to yield a predetermined pivoting angle around the fulcrum axis of the hinge unit.
Preferably, the hinge unit includes first and second hinge arms respectively including an elongate portion and an end portion.
The first and second hinge arms are preferably connected to each other around the fulcrum axis through the respective end portions, in a freely pivotable manner, and the first and second elongate portions respectively include several frame-fitting devices arranged in the length direction thereof, through which the fixed and mobile frame units can be linked to each other in a freely mountable and removable manner.
Preferably yet, each of the at least one first panel and the corresponding at least second panel includes several sizes of holders corresponding to different wire harness sizes to be tested.
Suitably, the fixed frame unit includes two elongated fixed members and two short fixed members, while the mobile frame unit includes two corresponding elongated and short mobile members.
The two elongated fixed members respectively include a first panel-fitting face with several panel-fitting device provided in a length direction thereof, while the two elongated mobile members respectively include a second panel-fitting face with several panel-fitting devices provided in a length direction thereof, whereby the first panel-fitting faces and the second panel-fitting faces are fitted with corresponding first panels and second panels.
One of the short fixed members and the corresponding short mobile member respectively include a hinge-fitting face with several arm-fitting means provided in a length direction thereof, through one of which is fixed the elongate portion of the corresponding hinge arm, such that the predetermined pivoting angle can be selected as desired.